The MS St. Louis was a German ocean liner which sailed out of Hamburg into the Atlantic Ocean in the summer of 1939 carrying more than 900 mostly wealthy Jewish refugees seeking asylum from the Third Reich. Following abortive attempts to land in several countries, most notably Cuba and the United States, the ship sailed back to Germany, whereupon various European nations each agreed to admit a small number of its passengers, the vast majority of whom ended up perishing in the Holocaust as most of the host countries came under Nazi occupation at some point during World War II, which started only a few weeks after the ship's return to Hamburg.

The ship's voyage caused the greatest controversy in the United States: Initially President Franklin Delano Roosevelt expressed a willingness to take in those on board, but virulent opposition from Southern Democrats — some of whom went so far as to threaten to withhold their support of Roosevelt in the 1940 Presidential election if this occurred — forced Roosevelt to refuse to let the ship, which had been hovering in the Caribbean Sea between Florida and Cuba, land in America. Negotiations with the Cuban government then took place, but broke down at the last minute, prompting the captain to head back across the Atlantic.